Digital Image Acquisition Device with Built in Dust and Sensor Mapping Capability

ABSTRACT

A digital image acquisition device has an image acquisition sensor, a shutter, an aperture and optical elements for focusing an image on the sensor. The device includes a light source located in the body of the device. The light source is periodically activated with one of the aperture or shutter closed, and the device derives a map of defects on the surface of the sensor from a calibration image acquired by the sensor when illuminated by the light source.

PRIORITY

This application is a Continuation of U.S. patent application Ser. No.11/674,650, filed Feb. 13, 2007, which claims the benefit of priorityunder 35 USC §119 to U.S. provisional patent application No. 60/773,714,filed Feb. 14, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a digital image acquisition device, andin particular a camera, such as for example a digital single lens reflex(DSLR) camera, which is configured to mitigate problems that wouldotherwise be caused by dust particles or other defects in the electronicsensor of the acquisition device.

2. Description of the Related Art

A map of defects caused by dust particles present in optical elements ofa digital image acquisition device may be generated, and used inprocessing images captured by the device. For example, FIG. 1 of USpublished patent application no. 2003/0193604 to Robins, which is herebyincorporated by reference, illustrates a set of LEDs 38 or 38 a disposedwithin camera lens elements 42, 44, 46 and, with the lens cover 36, 36 ain place, lighting the LEDs and acquiring a calibration image from thecamera sensor to detect contamination of the camera lens elements.

In addition, published PCT application no. PCT/EP2004/010199, which isassigned to FotoNation and corresponding to one or more of sevensequentially numbered U.S. published applications nos. 2005/0068446-452,and no. 2005/0078173, all of which are hereby incorporated by reference,discloses building a statistical dust map based on information derivedfrom one or more images acquired by a camera.

SUMMARY OF THE INVENTION

A digital image acquisition device has an image acquisition sensor, ashutter, optical elements for focusing an image on the sensor, and anaperture disposed between the optical elements and the shutter. Thedevice also includes a light source located in the body of the deviceand arranged to be periodically activated when the lens cap, shutter oraperture is closed. A map of defects in the sensor and on the surface ofthe sensor is derived from a calibration image acquired by the sensorwhen illuminated by the light source.

The device may be arranged to activate the light source in one or acombination of the following events: just before taking an image of ascene; or during inactivity of the device in accordance with apredefined schedule; or just after each turn-ON of the device; or when alens is replaced; or after each Nth image of a scene is captured, whereN is preferably between 3 and 10.

The sensor may include a CCD or a CMOS array. The light source mayinclude one or more LEDs.

The light source may be disposed between the sensor and the shutter. Thedevice may be arranged to activate the light source when the shutter isclosed.

The light source may be disposed between the shutter and the aperture.The device may be arranged to activate the light source when theaperture is closed and when the shutter is open.

The device may be arranged to activate the light source when the lens iscovered by a lens cap.

The device may be arranged to compare two images captured by the sensorwhen illuminated by the light source, and responsive to the imagesdiffering by greater than a threshold amount, to derive the map ofdefects.

The device may be arranged to analyze an image captured by the sensorwhen illuminated by the light source, and responsive to the imageincluding greater than a threshold amount of defects, to derive the mapof defects.

The device may be arranged to map the calibration image to the map ofdefects in association with a device specific look-up table.

The calibration image may be a low resolution or a full resolutionimage, and may be a full color or grayscale image.

The device may include a body and a removable lens. The optical elementsand the aperture may be part of the removable lens and the light sourcemay be located with the body.

The device may be arranged to correct an image of a scene in accordancewith the map of defects.

The device may be arranged to inform the user of a need to physicallyde-dust the device due to excess dust beyond reasonable digitalcorrection. The device may be further arranged to construct a second mapof defects of the optical elements, and may be arranged to correct thecorrected image in accordance with the second map.

The device may be arranged to store the map of defects with an image ofa scene.

The map of defects may include a binary, a gray level or a probabilisticimage. A further digital image acquisition device is provided. Thedevice includes a camera body configured for coupling with a lensassembly. An electronic image sensor is disposed within the camera body.A shutter controls exposure of the sensor by ambient light. A lightsource is disposed between the sensor and any lenses of the lensassembly for illuminating the sensor. A processor and is programmed bystored instructions to control the light source to illuminate the sensorand to create a sensor defect map based on a calibration image acquiredby the sensor when illuminated by the light source.

The device may further comprise the lens assembly coupled with thecamera body. The lens assembly may include an aperture and one or morelenses. The processor may be programmed to initiate illumination of thesensor and create the sensor defect map when the aperture is closed. Theshutter may be disposed between the light source and the sensor, whereinthe shutter would be open when the sensor is illuminated for creatingthe sensor defect map.

The device may include a lens cap for coupling with the lens assemblythereby preventing exposure of the sensor by ambient light traversingthe lens assembly. The processor may be programmed to initiateillumination of the sensor for creating the sensor defect map when thelens cap is coupled to the lens assembly.

The light source may be disposed between the shutter and the sensor, orthe shutter may be disposed between the sensor and the light source.

The processor may be programmed to initiate illumination of the sensorfor creating the sensor defect map when the shutter is closed and/orjust before an image of a scene is acquired by the device and/or on apredetermined schedule during inactivity of the device.

The processor may be programmed to interpret coupling of the lensassembly to the camera body and/or turning-on the device as a triggerfor initiating illumination of the sensor for creating the sensor defectmap.

The processor may be programmed to automatically update an existingsensor defect map upon creation of a new sensor defect map. Both theexisting and new sensor defect maps may be stored for application toimages acquired at different times.

The light source may be built into the camera body.

A look up table may be stored in the camera body for providing a mappingfrom an acquired calibration image to a real sensor defect position map.

A method of correcting acquired digital images for detected sensordefects is also provided. A camera body is configured for coupling witha lens assembly and contains an electronic image sensor, and a lightsource. The sensor and light source are optically enclosed therebypreventing exposure of the sensor by ambient light. A calibration imageacquired by the sensor is detected when illuminated by the light source.A sensor defect map is created based on the calibration image.

Exposure of the sensor by ambient light by enclosing the light sourcemay be controlled by a camera body shutter, a lens aperture, a lens cap,an on/off camera switch, a predetermined schedule, or a lens assemblycoupling detection switch, or combinations thereof.

A lens assembly may be coupled to the camera body.

The light source may be disposed between a lens aperture and a camerabody shutter, and the shutter may be disposed between the light sourceand the sensor. The optical enclosing may include closing the aperture,and the illuminating may include opening the shutter.

The light source may be disposed between a camera body shutter and thesensor, and the optical enclosing may include closing the shutter.

An acquired calibration image may be mapped to a real sensor defectposition map.

An existing sensor defect map may be automatically updated upon creatinga new sensor defect map.

One or more digital storage devices having digital code embodied thereinfor programming one or more processors to perform a method of correctingacquired digital images for detected sensor defects as recited hereinabove or below.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described by way of examplewith reference to the accompanying drawings, in which:

FIG. 1 shows the camera system as disclosed in US published applicationno. 2003/0193604;

FIG. 2 shows a digital image acquisition device according to certainembodiments;

FIG. 3 shows a flow diagram illustrating the operation of the camerafirmware; and

FIG. 4 shows a further digital image acquisition device according tocertain embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A digital image acquisition device according to one embodiment isprovided with an image acquisition sensor, preferably a CMOS or CCDarray (herein generically referred to CCD), a shutter, an aperture andone or more optical elements for focusing an image on the sensor. Thedevice includes an internal light source, e.g., an LED or LED array,located in the body of the device, preferably between the sensor and theshutter. The device is arranged to activate the light source for a shortperiod of time in accordance with a predefined criteria which can beeither just before taking an image of a scene, or at any moment duringinactivity of the device (in accordance with a predefined schedule), orjust after each turn-ON of the device, or after a change of lens isdetected or any combination of the criteria above, and to derive a mapof defects on the surface of the sensor from a calibration imageacquired by the sensor when illuminated by the light source.

An optical solution is provided for automatically building a dust map inDSLR cameras.

Continuous automatic updating of the dust map is also provided in suchcameras to mitigate problems of new dust spots appearing or old dustparticles migrating on the CCD surface. In such embodiments, the deviceis arranged to automatically detect the need to re-calibrate the dustmap by comparing different calibration images acquired by the sensorwhen lit by the light source.

When either a preview or a full resolution image is acquired while thesensor is lit by the light source, the obtained calibration image willbe uniform enough to allow construction of a map of dust related defectson the CCD sensor surface. Even if the CCD surface is not uniformly lit(as a consequence of an off-center LED) the non-uniformity ispersistent, and can be thus accounted for in a map or a formula that canbe stored (in a compressed form) in a lookup table for mapping acalibration image to a final dust map.

In one embodiment, the optical elements are part of a removable lens. Bybuilding the light source into a camera body, an advantageous camera canbe arranged to receive multiple interchangeable lenses, which is costeffective. This was not considered by Robins in the 2003/0193604application, which related to a digital camera with an integral lens.

A technique in accordance with an embodiment may be implementedautomatically, whereas Robins requires the user to put the lens cover inplace before calibration.

A technique in accordance with another embodiment involves the formationof the calibration image directly from the light source, some of whichmay be obscured by dust or other defects. In Robins, the calibrationimage is obtained from rays that are reflected by lens contaminants.

A technique in accordance with another embodiment can work with both theaperture and the shutter closed, because in this embodiment, the lightsource disposed between the sensor and both the aperture and theshutter. In Robins, both the aperture and the shutter must be open toacquire the calibration image, because the aperture and shutter ofRobins are located between the light source and sensor.

Another embodiment includes the light source not being focused using theoptical system, such that the solution is not dependent on the opticalnature of any lenses, and thus computational compensation for variouszoom factors or lenses with different focal lengths is obviated.

In alternative embodiments, where the space between the shutter and theCCD sensor is too small, the LEDs can be placed within the camera bodybetween the lens assembly and the shutter. In this case, the shutter isopened, even if not necessarily the aperture, when acquiring thecalibration image for the dust map.

In an alternative embodiment, the device may be programmed to activatean LED and capture an image only when the lens cap is on, such that noexternal light can diffuse the shadows created by the LED light.

Once the calibration image is obtained as described above, a dustdetection algorithm can be used to construct a dust map for the lenselements. So, for example, when an image of a scene is acquired, the CCDdust map can be used to correct CCD defects, and then a statistical dustmap may be provided in accordance with PCT Application No.PCT/EP2004/010199 or US published application no. 2005/0078173, whichare hereby incorporated by reference and assigned to the same assigneeas the present application, can be used to correct for image defectscaused by dust particles in the optical elements. By contrast, Robinsdoes not disclose a technique for distinguishing between (a) imagedefects resulting from particles or imperfections on the sensor; and (b)lens element-related defects which ought to be treated differently,especially as the effect of the latter varies more greatly as imageacquisition parameters such as focal length and aperture change.

A calibration method in accordance with another embodiment can also beused to detect defects in the sensor also known as “dead-pixels” and“burned pixels”.

Referring now to FIG. 2, in a preferred embodiment, a small light source210 (e.g., a LED) is mounted within a camera body 200 between a CCDsensor 52 and a shutter 50. Illumination of the light source 210, and/orcontrol of other aspects of camera functionality (not shown) iscontrolled by camera firmware 220 or other program media. In a preferredembodiment, the camera body 200 receives an interchangeable lens 240including lens elements 42, 44 and 46 and aperture 48, which may havesimilar in functionality to the corresponding elements of FIG. 1, exceptthat in Robins the lens is integral with the camera body. Again, thecamera firmware 220 preferably controls the operation of the lens 240including setting and reading image acquisition parameters includingfocal length and aperture as described elsewhere.

In an embodiment, the firmware is arranged to periodically illuminatethe light source 210 when the shutter 50 is closed, and to store acalibration image acquired by the sensor. In this embodiment, the sourcelight 210 is not central with respect to the sensor 52. As such, thecamera firmware includes a look-up table 250 specific to the cameramodel to provide a mapping from an acquired calibration image to thereal dust position on the CCD sensor. This real dust positioninformation is stored in a map 260. In general, the mapping shifts thecalibration image in a direction towards the light source to compensatefor non-uniform illumination of the sensor due to the fact that thelight source 210 may not be central or uniform with respect to thesensor.

An exemplary operation of the firmware 220 is illustrated in FIG. 3. Abackground or event driven process begins during a camera idle period300, for example, just before taking an image of a scene, or at anymoment during inactivity in accordance with a predefined schedule, orjust after each turn-ON, or the process can run every N pictures, sayfor N between 3 and 10, or a combination of these or other events suchas putting on a lens cap or turning the camera off or just after takingan image. In any case, once initiated, the process then causes thesource 210 to illuminate the sensor 52 with the shutter closed 310. Acalibration image is then acquired 320 and can either be stored involatile or non-volatile memory for whatever predetermined duration.

The calibration image can first be checked for an aggregate number ofdefects, and if these exceed a threshold, an alarm can be provided 340to the user to service the camera body. The threshold can be based on asimple integral or average of image luminance or indeed a count ofdiscrete defects. If an alarm is registered, the process can eithercontinue or terminate.

When the process continues, the calibration image can then be compared350, 360 with a previous calibration image, if available, to determineif greater than a significant degree of change has occurred. If not 370,the process can terminate before running again at a later time/event.

If a new dust map is desired or it is otherwise determined by thefirmware, manually, or due to the occurrence of a specific event orpassage of time, to generate a new dust map, then the calibration imageis mapped through the look-up table 250 to produce the dust map 260. Themapping from the calibration image to the dust map takes into accountthe difference in the effect of the light from the source 210 on sensordefects compared to the effect of light through the aperture 48 andshutter 50 on sensor defects when acquiring an image normally.

It will be seen that the calibration image 250 and/or dust map 260 canbe processed either as a binary image, with defects either occluding thesensor or not, or as a gray scale or probabilistic type image accordingto the nature of image correction that may be performed later whenprocessing/correcting normally acquired images using the dust map.

The current dust map 260 can be stored either in volatile ornon-volatile memory, for later use in processing acquired images. Ifstorage space is at a premium, the firmware can overwrite thecalibration image 250 information with the dust map 260.

In any case, once the dust map has been determined, the camera canacquire images as normal at 400. In a preferred embodiment, the dust map260 or a pointer to the dust map can be saved with each acquired image410. For example, for JPG files, the map can be stored in a MakerNoteexif tag. A pointer to a dust map is useful where many acquired imagesmay be associated with the same dust map. In such cases, severalversions of dust maps may be stored with different acquired imagesincluding pointers to different maps.

At any suitable time after an image has been acquired, it can becompared with the dust map 260 to identify and/or correct defects in theimage resulting from sensor defects 420. Where camera click-to-clickinterval is critical, this processing is likely to be performed in thebackground during periods of camera inactivity. It is also possible thatthe dust map could be used both to analyze and correct low resolutionpreview or post-view images as well as full resolution acquired images.

In any case, once an acquired image has been corrected for sensordefects, image processing software or firmware can then continue byusing techniques disclosed in, for example, the PCT Application No.PCT/EP2004/010199, incorporated by reference above, to detect andcorrect at 430 for image defects resulting from dust artifacts in theimage acquisition optics. It will be seen that alternativeimplementations are possible. For example, the light source 210 can emitin any region of the spectrum in which the CCD is sensitive, forexample, infrared. Also, many LEDs (230), for example, four, six, eight,etc., may be used to obtain a symmetrical illumination of the CCD,although some calibration may still be required in such cases to takeinto account the difference in such illumination from light through theaperture 48 and shutter 50. The light source or sources may move, e.g.,with the closing of the shutter or with separate mechanics, from beingout of the way for the device to take a picture to a position wherein abetter calibration image may be taken.

What follows is a cite list of references which are, in addition to thatwhich is described as background, the invention summary, the abstract,the brief description of the drawings and the drawings, and otherreferences cited above, hereby incorporated by reference into thedetailed description of the preferred embodiments as disclosingalternative embodiments:

U.S. Pat. Nos. 6,035,072; 7,599,577;

United States published patent applications nos. 2005/0068445,2005/0068452, 2006/0039690, 2006/0098890, 2006/0098237, and2006/0098891; 2008/0240555; and

U.S. provisional patent application Nos. 60/773,714, and 60/821,956.

While an exemplary drawings and specific embodiments of the presentinvention have been described and illustrated, it is to be understoodthat that the scope of the present invention is not to be limited to theparticular embodiments discussed. Thus, the embodiments shall beregarded as illustrative rather than restrictive, and it should beunderstood that variations may be made in those embodiments by workersskilled in the arts without departing from the scope of the presentinvention, as set forth in the appended claims and structural andfunctional equivalents thereof.

In addition, in methods that may be performed according to the claimsbelow and/or preferred embodiments herein, the operations have beendescribed in selected typographical sequences. However, the sequenceshave been selected and so ordered for typographical convenience and arenot intended to imply any particular order for performing theoperations, unless a particular ordering is expressly provided orunderstood by those skilled in the art as being necessary.

1. A digital image acquisition device having an image acquisitionsensor, a shutter, one or more optical elements for focusing an image onthe sensor, and an aperture disposed between at least one of said one ormore optical elements and said shutter, the device including a lightsource located in a body of the device, and being arranged toperiodically activate the light source only when said aperture is closedsuch that said sensor is substantially unexposed to ambient light, andto derive a map of defects in the sensor or on the surface of thesensor, or both, from a calibration image acquired by the sensor whenilluminated by the light source and when said sensor is substantiallyunexposed to ambient light due to said aperture being closed, and thedevice is further arranged to correct an acquired image based on the mapof defects, and to construct a second defect map based on a secondcalibration image, and to correct a further image in accordance withsaid second defect map.
 2. A digital image acquisition device accordingto claim 1, wherein the device is arranged to activate the light sourcein one or a combination of the following events: just before taking animage of a scene; or during inactivity of the device in accordance witha predefined schedule; or just after each turn-ON of the device; or whena lens is replaced; or after each Nth image of a scene is captured.
 3. Adigital image acquisition device according to claim 2, where N isbetween 3 and
 10. 4. A digital image acquisition device according toclaim 1, wherein said sensor comprises one of a CCD or a CMOS array. 5.A digital image acquisition device according to claim 1, wherein saidlight source comprises one or more LEDs.
 6. A digital image acquisitiondevice having an image acquisition sensor, a shutter, one or moreoptical elements for focusing an image on the sensor, and an aperturedisposed between at least one of said one or more optical elements andsaid shutter, the device including a light source located in a body ofthe device, and being arranged to periodically activate the light sourcewhen one of a lens cap, shutter or said aperture is closed, or acombination thereof, and to derive a map of defects in the sensor or onthe surface of the sensor, or both, from a calibration image acquired bythe sensor when illuminated by the light source, wherein said lightsource is disposed between the sensor and both the aperture and theshutter, and wherein the device is arranged to activate the light sourcewhen the aperture or shutter, or a combination thereof, is closed, andthe device is further arranged to correct an acquired image based on themap of defects, and to construct a second defect map based on a secondcalibration image, and to correct a further image in accordance withsaid second defect map.
 7. A digital image acquisition device accordingto claim 1, wherein said light source is disposed between the shutterand the aperture, and wherein the device is arranged to activate thelight source when the aperture is closed and when the shutter is open.8. A digital image acquisition device according to claim 1, wherein saiddevice is arranged to activate said light source when the opticalelements are covered by the lens cap.
 9. A digital image acquisitiondevice according to claim 1, wherein the device is arranged to comparetwo images captured by the sensor when illuminated by the light source,and responsive to said images differing by greater than a thresholdamount, to derive said map of defects.
 10. A digital image acquisitiondevice according to claim 1, wherein the device is arranged to analyzean image captured by the sensor when illuminated by the light source,and responsive to said image including greater than a threshold amountof defects, to derive said map of defects.
 11. A digital imageacquisition device according to claim 1, wherein said device is arrangedto map said calibration image to said map of defects in association witha device specific look-up table.
 12. A digital image acquisition deviceaccording to claim 1, wherein said calibration image comprises a lowresolution image or a full resolution image.
 13. A digital imageacquisition device according to claim 1, wherein said calibration imagecomprises a full color image or a grayscale image.
 14. A digital imageacquisition device according to claim 1, further comprising a body thatcontains said light source and a removable lens that comprises at leastone of said one or more optical elements and said aperture.
 15. Adigital image acquisition device according to claim 1, wherein thedevice is arranged to correct an image of a scene in accordance withsaid map of defects.
 16. A digital image acquisition device according toclaim 15, wherein the device is arranged to inform the user of a need tophysically de-dust said device due to excess dust beyond reasonabledigital correction
 17. A digital image acquisition device according toclaim 1, wherein the device is arranged to store said map of defectswith an image of a scene.
 18. A digital image acquisition deviceaccording to claim 1, wherein said map of defects comprises a binary, agray level or a probabilistic image, or combinations thereof.
 19. Adigital image acquisition device, comprising: a camera body configuredfor coupling with a lens assembly including one or more lenses and anaperture; an electronic image sensor within the camera body; a shutterfor controlling exposure of the sensor by ambient light; a light source,disposed between the sensor and both said shutter and said aperture, forilluminating the sensor; a processor; and one or more digital storagedevices having instructions embedded therein for programming theprocessor to: control the light source to illuminate the sensor onmultiple occasions only when said shutter or said aperture, or acombination thereof, is closed such that said sensor is substantiallyunexposed to ambient light; create a sensor defect map based on acalibration image acquired by the sensor when illuminated by the lightsource and when said sensor is substantially unexposed to ambient lightdue to said shutter or aperture, or combination thereof, being closed;correct an acquired image based on the sensor defect map; construct asecond defect map based on a second calibration image; and correct asecond image in accordance with said second defect map.
 20. The deviceof claim 19, further comprising said lens assembly coupled with saidcamera body.
 21. The device of claim 20, wherein the processor isprogrammed to initiate illumination of the sensor and creation of thesensor defect map when the aperture is closed.
 22. The device of claim21, wherein the shutter is disposed between the light source and thesensor, and the shutter is open when the sensor is illuminated forcreating the sensor defect map.
 23. The device of claim 20, furthercomprising a lens cap for coupling with the lens assembly therebypreventing exposure of the sensor by ambient light traversing the lensassembly.
 24. The device of claim 23, wherein the processor isprogrammed to initiate illumination of the sensor for creating thesensor defect map when the lens cap is coupled to the lens assembly. 25.A digital image acquisition device, comprising: a camera body configuredfor coupling with a lens assembly including one or more lenses and anaperture; an electronic image sensor within the camera body; a shutterfor controlling exposure of the sensor by ambient light; a light source,disposed between the sensor and the one or more lenses of the lensassembly, as well as between the sensor and both the shutter and theaperture, the light source for illuminating the sensor on multipleoccasions when a lens cap is on, or the shutter or the aperture isclosed, or combinations thereof; a processor; and one or more digitalstorage devices having instructions embedded therein for programming theprocessor to: control the light source to illuminate the sensor; createa sensor defect map based on a calibration image acquired by the sensorwhen illuminated by the light source; correct an acquired image based onthe sensor defect map; construct a second defect map based on a secondcalibration image; and correct another image in accordance with saidsecond defect map.
 26. The device of claim 25, wherein the processor isprogrammed to initiate illumination of the sensor for creating thesensor defect map when the shutter is closed.
 27. The device of claim26, wherein the processor is programmed to interpret coupling of thelens assembly to the camera body acts as a trigger for said initiatingillumination of the sensor for creating the sensor defect map.
 28. Thedevice of claim 26, wherein the processor is programmed to initiate saidillumination of the sensor for creating the sensor defect map justbefore an image of a scene is acquired by the device.
 29. The device ofclaim 26, wherein the processor is programmed to initiate saidillumination of the sensor for creating the sensor defect map on apredetermined schedule during inactivity of the device.
 30. The deviceof claim 26, wherein the processor is programmed to interpret turning-onthe device as a trigger for initiating illumination of the sensor forcreating the sensor defect map.
 31. The device of claim 19, wherein theprocessor is programmed to automatically update an existing sensordefect map upon creation of a new sensor defect map.
 32. The device ofclaim 31, wherein the both the existing and new sensor defect maps arestored for application to images acquired at different times.
 33. Thedevice of claim 19, wherein the light source is built into the camerabody.
 34. The device of claim 19, further comprising a look up tablestored therein for to provide a mapping from an acquired calibrationimage to a real sensor defect position map.
 35. A method of correctingacquired digital images for detected sensor defects, comprising:providing a camera body that is configured for coupling with a lensassembly and that contains an electronic image sensor, and a lightsource; optically enclosing the sensor and light source therebypreventing exposure of the sensor by ambient light, including closing anaperture of the lens assembly; only while said sensor and light sourceare optically enclosed due to said closing of said aperture,illuminating the sensor with the light source on multiple occasions;detecting a calibration image acquired by the sensor when illuminated bythe light source on a first occasion; and creating a sensor defect mapbased on the calibration image, generating a corrected image based on anacquired image and the sensor defect map; constructing a second defectmap based on a further calibration image acquired by the sensor on asecond occasion; and correcting another image in accordance with saidsecond defect map.
 36. The method of claim 35, wherein preventingexposure of the sensor by ambient light by enclosing the light source iscontrolled by a camera body shutter, a lens aperture, a lens cap, anon/off camera switch, a predetermined schedule, or a lens assemblycoupling detection switch, or combinations thereof.
 37. The method ofclaim 35, further comprising coupling the lens assembly to the camerabody.
 38. The method of claim 35, wherein the light source is disposedbetween a lens aperture and a camera body shutter, and the shutter isdisposed between the light source and the sensor, and wherein theoptical enclosing comprises closing the aperture, and the illuminatingfurther comprises opening the shutter.
 39. A method of correctingacquired digital images for detected sensor defects, comprising:providing a camera body that is configured for coupling with a lensassembly and that contains an electronic image sensor, and a lightsource; optically enclosing the sensor and light source therebypreventing exposure of the sensor by ambient light, wherein the lightsource is disposed between both a camera body shutter and aperture ofthe lens assembly, and the sensor, and wherein the optical enclosingcomprises closing the shutter; illuminating the sensor with the lightsource on multiple occasions; detecting a calibration image acquired bythe sensor when illuminated by the light source; creating a sensordefect map based on the calibration image; and generating a correctedimage based on an acquired image and the sensor defect map; constructinga second defect map based on a further calibration image acquired by thesensor on a second occasion; and correcting another image in accordancewith said second defect map.
 40. The method of claim 35, furthercomprising mapping an acquired calibration image to a real sensor defectposition map.
 41. The method of claim 35, further comprisingautomatically updating an existing sensor defect map upon creating a newsensor defect map.
 42. One or more digital storage devices havingdigital code embodied therein for programming one or more processors toperform a method of correcting acquired digital images for detectedsensor defects, the method comprising: initiating an optical enclosureof an image sensor and a light source thereby preventing exposure of thesensor by ambient light, including closing an aperture; during saidoptical enclosure of said image sensor due to said closing of saidaperture, illuminating the sensor with the light source on multipleoccasions; detecting a calibration image acquired by the sensor whenilluminated by the light source; and creating a sensor defect map basedon the calibration image; and generating a corrected image based on anacquired image and the sensor defect map; constructing a second defectmap based on a further calibration image acquired by the sensor on asecond occasion; and correcting another image in accordance with saidsecond defect map.
 43. The one or more storage devices of claim 42,wherein preventing exposure of the sensor by ambient light by enclosingthe light source is controlled by a camera body shutter, a lensaperture, a lens cap, an on/off camera switch, a predetermined schedule,or a lens assembly coupling detection switch, or combinations thereof.44. The one or more storage devices of claim 42, the method furthercomprising coupling the lens assembly to the camera body.
 45. The one ormore storage devices of claim 42, wherein the light source is disposedbetween a lens aperture and a camera body shutter, and the shutter isdisposed between the light source and the sensor, and wherein theoptical enclosing comprises closing the aperture, and the illuminatingfurther comprises opening the shutter.
 46. One or more digital storagedevices having digital code embodied therein for programming one or moreprocessors to perform a method of correcting acquired digital images fordetected sensor defects, the method comprising: initiating an opticalenclosure of an image sensor and a light source thereby preventingexposure of the sensor by ambient light, wherein the light source isdisposed between a camera body shutter and the sensor, and wherein theoptical enclosing comprises closing the shutter; illuminating the sensorwith the light source periodically at equal intervals of at least oneday; detecting a calibration image acquired by the sensor whenilluminated by the light source; and creating a sensor defect map basedon the calibration image; and generating a corrected image based on anacquired image and the sensor defect map; constructing a second defectmap based on a further calibration image acquired by the sensor on asecond occasion; and correcting another image in accordance with saidsecond defect map.
 47. The one or more storage devices of claim 46, themethod further comprising mapping an acquired calibration image to areal sensor defect position map.
 48. The one or more storage devices ofclaim 46, the method further comprising automatically updating anexisting sensor defect map upon creating a new sensor defect map.